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Jacynthe Bouchard doesn't dare dig weeds or trim foliage in the Japanese-style garden outside her Victoria home without taking precautions.

She wears long sleeves, takes antihistamine and asthma medication, rubs pollen-blocking cream around her nostrils, and changes into her gardening clothes in the basement to avoid spreading allergens through the house.

Then she puts her mask on.

The pollen-filtering mask her husband discovered in a paint shop has been "a saviour" for her as a gardener, Ms. Bouchard says.

She didn't indulge in her passion for years after she was hospitalized due to bronchial damage caused by a severe allergic reaction to pollen and moulds while gardening. But as a masked gardener, she admits, "you do get funny looks."

For green thumbs like Ms. Bouchard, allergies to tree and grass pollens, bee stings, moulds, weed saps and strong scents can be a torment.

Even so, there are plenty of ways to manage allergies without giving up the joys of gardening, says Thomas Leo Ogren, a horticulturalist based in San Luis Obispo, Calif., who has studied allergens for three decades.

One approach is to use allergen-avoidance tactics such as wearing protective gear or gardening on calm days after heavy rains, he says.

The other is to plant a low-allergen garden.

Mr. Ogren encourages allergic gardeners to practise "botanical sexism" by choosing mainly female plants for their garden of Eden. Only male plants produce pollen, he points out, and "female plants, by their very nature, are designed to trap pollen."

A hedge of female yew will capture ambient allergens blowing from city streets, he says, and help restore the gender balance in urban areas.

In recent decades, cities all over North America have planted row upon row of male bushes and trees to avoid the cost of cleaning up messy seeds and fruit, he adds. "This is what's driving high pollen counts in urban areas."

But choosing female plants is easier said than done. Most trees are produced asexually from patented clones, Mr. Ogren explains. Since few plant nurseries discriminate by gender, the sex of a plant may be tough to determine unless it's seeding or fruiting (which indicate it's female).

To make things easier, he has identified the predominant sex of hundreds of individual cultivars and included them in an allergy ranking of 3,500 plants in his book Allergy-Free Gardening.

Determining a plant's potential to trigger allergies isn't a just matter of doing pollen counts, says Mr. Ogren, who considered 150 different criteria in his ranking system.

Rhododendrons and azaleas are not heavy pollen makers, for example, but the powders they produce are highly toxic. "I would never plant them outside a bedroom window."

Mr. Ogren notes that the chemotherapy drug Taxol is derived from the yew tree. He's had clients complain of symptoms such as headaches and fatigue, which he attributed to pollen from male yews blowing through a window all night long.

Exposure can be significant, he says, "but it never comes up on any allergist's radar."

Aside from pollens, strong botanical scents such as oil of rosemary bother some gardeners, particularly asthmatics. Touching certain plants, such as hydrangea, can cause itchy skin, while the milky sap of common weeds such as spurge is highly allergenic for many people, Mr. Ogren says.

Contrary to popular belief, allergic gardeners needn't rip out their lawns to avoid grass pollens. In fact, "a well-maintained lawn is a very good pollen trap."

Many grass varieties that grow well in Canada don't produce pollen until they're much taller than the average lawn, including certain types of fescue. For a soft texture and easy maintenance, Mr. Ogren recommends a female clone of buffalo grass, which grows in dryer regions and can be mowed as little as three times a season.

In choosing plants, safe bets include the female trees of holly, willow, poplar and ash; certain perennials, such as peonies; and annuals including petunias and impatiens.

If replanting isn't an option, gardeners might be better off wearing allergy combat gear like Ms. Bouchard. Her garden was beautifully landscaped when she bought her home several years ago, she says, and she was loath to redo the flower beds, rock gardens, treed areas and goldfish pond.

In her mask, passersby during the H1N1 virus scare mistook her for a germaphobe, Ms. Bouchard recalls. But the pollen-filtering headgear allows her to garden for up to five hours at a stretch, compared to 10 minutes without covering her face.

"In my case, it does the trick."

Tips for allergic gardeners

Change clothes right after gardening; shower and wash hair to remove allergens.

Use gravel or oyster shells around plants instead of wood-based mulch, which retains moisture, promoting moulds.

Attract birds to the garden to eat insects that trigger allergies.

Ask a non-allergic family member to mow lawns and deal with compost, a breeding ground for moulds.

Keep house windows closed during mowing and for a few hours afterward.

Sources: Asthma and Allergy Foundation of America,

Recommended plants

Forget-me-nots ( Myosotis)

Petunia ( Petunia)

Pansy, violet ( Viola)

Spring-flowering crocus (Crocus)

Gladiolus ( Gladiolus)

Peony ( Paeonia)

Hens-and-chicks ( Sempervivum)

Fuchsia ( Fuchsia)

Poppy ( Papaver)

Chinese lantern ( Physalis)

Plants to avoid:

Chrysanthemum, daisy varieties ( Chrysanthemum)

Oakleaf and PeeGee hydrangeas ( Hydrangea quercifolia and H. paniculata)

Buttercup ( Thalictrum)

Queen Anne's lace ( Daucus carota)

Edelweiss ( Leontopodium alpinum)

Tansy ( Tanacetum)

Lilac ( Syringa)

Lavender ( Lavandula)

Pot marigold ( Calendula)

Ivy ( Hedera)

Source: Allergy-Free Gardening by Thomas Leo Ogren